A lot of the comments in this thread are ludicrous. I was a Mac user for about 8 years and last year I switched to a windows based PC. I built the PC myself, with my choice of hardware and my choice of case. I switched because after using Windows 7 on a mac via bootcamp I realised just how much windows had improved over previous version (which I admit were pretty poor, the reason I went to mac) but windows 7 has been very very stable. Its been very fast and I find it far more usable then OSX in a massive way.
I experienced more crashes on macs then I have experienced on my PC, which has been so stable its laughable that people call them unstable. Not one BSOD, not one full system lock up. Granted programs have crashed, but don't try and even pretend you havn't had applications crash.
I don't dislike macs, infact, my parents use my old iMac and I still think its a great machine, and I personally own an iPhone and an iPad. But please, so many users on here need to get there head out of there arse. It constantly sounds like your trying to justify your purchase. If you prefer the mac then thats great, but don't jump on the "omg PC's are **** look at my cool mac, im so cool" bandwagon. It's boring, shows just how clueless so many users are about technology and makes me feel embarrassed for you.
Granted I need to run an Antivirus on my PC, but I just run MSE and apply actual common sense to my computer usage (as in don't download that email called freeporn.exe) and I've yet to have a virus at all. In terms of security... its actually pretty laughable that OSX is always the first to go down in the Pwn2Own competitions, as well as any mac software such as the safari browser (chrome it up people) which I only discovered in the past few weeks.
If you are happy with your macs, thats great, they are great machines. Just leave out the "im so superior" attitude.